Administration of local anesthetics is daily routine for most dental practitioners. Normally, the effect is achieved, and no adverse effects are seen. In this article, the authors describe the complications of immediate, intense and shooting pain, numbness, and marked pallor of the cheek, which occurred during infiltration of a local anesthetic in buccal vestibule infiltration. The patients moved suddenly because of pain and marked pallor of the cheek near the root of the nose and lower eyelid pallor was observed. The pain was very short and the injection was performed again after a few minutes. Two patients also reported an alteration of vision or paralysis of the extra-ocular muscles and drooping eyelid due to paralysis of the levator palpebrae superioris muscle and signs of numbness in the infraorbital area on the same side as the anesthesia. While 3 patients were also apprehensive and started to scare with heart palpitations, as they did not understand what was happening. Probably the anesthetic solutions were injected into an intravascular artery and passed from the extraosseous branch of posterior superior alveolar artery through to the infraorbital artery, which could produce the clinical signs observed in the present study. At the same time, the inoculation of anesthetic in the artery could be grounds for legal disputes for the dentist. In fact, in the absence of vascular disease, anomalies documented by the dentist, they would, however, respond to professional liability and be liable for damages caused to the patient. In conclusion, despite the fact that this condition requires no treatment, it could lead to the recognition of clinical signs in patient with injection of local anesthesia into the artery. At the same time, the inoculation of anesthetic in the artery could be grounds for legal disputes for the dentist.